


Smol Skellie

by DittoInHeat



Category: Undertale (Video Game)
Genre: Alpha/Beta/Omega Dynamics, Alpha/Omega, Bad Parenting, Bad Puns, Ecto-Genitalia (Undertale), Egg Laying, Established Alphys/Undyne, F/F, M/M, Papyrus Being Papyrus, Protective Sans, Sibling Incest, Skeleton Pregnancy (Undertale), Skeleton Puns, This Is Why We Can't Have Nice Things, Undyne Swearing, Why Did I Write This?
Language: English
Status: Completed
Published: 2018-08-06
Updated: 2018-11-04
Packaged: 2019-06-09 17:31:46
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 3,730
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15272649
Author URL: https://archiveofourown.org/users/DittoInHeat/pseuds/DittoInHeat
Summary: How would you react if you saw a tiny skeleton? Maybe the usual reaction from other monsters would be shock, disbelief, fascination, adoration, and maybe even.. fascination? Were their any skeletons that could conceive children? Well.. of course there were the brothers, but that couldn't be possible.. they're both boys! Or.. maybe it has something to do with.. magic anatomy. Who the hell knows!





	1. Chapter 1

The most important thing on both of the monsters minds were how important their support for each-other was right now. The taller of the two was constantly sick and tired, all magic being seeped from his being going to the growing pocket of energy in the ecto-chamber. The older of course tried his best to comfort his brother as much as possible, even calling Undyne and telling her that he came down with something. 

After coming home from work, he padded up the stairs to Papyrus' room slowly creaking the door open seeing his brother sleeping peacefully on his bed, light snores emitting past his teeth. Chuckling softly, he shuffled to the side of the bed, caressing the long skull, just admiring the features of a monster that usually doesn't sleep. It was oddly alluring and calming.

"heya paps, 'm home, ya holding up well?" Sans whispered, lightly tapping on the side of his skull to get his attention.

'Nyeh'ing softly, his eye-sockets slowly opened, smile becoming wide at seeing the familiar face next to him.

"SANS..! I MISSED YOU, AND I'M DOING GOOD, JUST..." He yawned "SLEEP, THAT'S ALL" His skull still resting on the pillow, he kept eyeing the older sibling with pure love and adoration.

Lifting the blanket carefully, exposing the inflated citrus colored chamber that connected from the lower-most ribs to the pelvis.

"gettin' kinda big, huh? i wonder what is' gon' look like.." Sans wondered, finger tips trailing lightly over the magic, earning a soft sigh from the one below his touch.

"MAYBE IT'S COMING SOON? I SURE HOPE SO.. THE GREAT PAPYRUS DOESN'T LIKE LAYING HERE ALL DAY.." He complained, huffing quietly.

"oh come on paps, don't be such a baby about this" Sans winked

"SANS NO-"

"what? was that joke a little.. premature?"

"NOOOOO!!" Papyrus whined, turning onto his side, facing away from Sans.

"aw come on bro, i know you like this, yer smilin'" Chuckling, he crawled onto the bed, kneeling next to Papyrus' back.

"I KNOW, AND I HATE IT!" He grumbled, feeling the bed dip at the added weight.

Crawling over his brother, he layed on top of his brothers side, trapping the taller monster beneath him, face relaxed and content, but also tired. Bones began to relax, laying even more into the form below him.

"SANS! YOU DON'T NEED TO DO THAT!" Papyrus flipped over, causing Sans to fall in-front of the monster, both now facing each-other.

"heh, thanks for helpin' me out bro.. ya always do" Snuggling into the form, staring up at his brother, than looking back at the ecto-chamber, worry began to tug at his thoughts.

"are ya sure that yer doin' fine? it's lookin' a little big there, paps.." Poking it tentatively, surprised at how compact and hard it began to feel.

"OF COURSE THE GREAT PAPYRUS FEELS FINE! NOTHING CAN EVER BRING ME DOWN! NYEH! HEH! HEH!" Striking a pose dramatically, even when laying down somehow.

"alright, 'm just uhh.. makin' sure.." Yawning, Sans began to doze off, Papyrus quickly following along as well, sharing the warmth between their magic.

 

\----------------

 

Jolted awake by an almost blood-curdling scream, Sans immediately jumped out of bed, magic flaring as to see where the attack came from. But when his eye landed on the bright glowing lump between the sheets, his magic immediately dissipated as fear and worry overcame his senses, rushing back to the bed and ripping off the blanket, seeing the shivering form laying on the bed, legs spread and eye-sockets actively leaking tears.

"SANS!! SOMETHING- SOMETHING'S WRONG!!" Papyrus screamed out, voice quickly becoming hoarse and weak.

"shit shit shit.." Sans cursed, quickly climbing back on the bed and between the spread legs, trying to see if his speculations were correct.

Papyrus' magic was conjured, leaking excess magic as the part was visibly contracting and loosening in a shaky rhythm. He reached for the hand clutching the sheets, interlacing the fingers with his own, trying to comfort his pained and frightful partner.

"ya gotta relax for me paps.. is' not gonna get better if you keep panicking like this, focus on how well our magic can mix.." Sans cooed, bones glowing a slight blue, swirling down his arms to Papyrus' form, the orange magic copied the rhythms, bathing each-other in the others' feelings.

Shivering at the fear and pain, he fought through it, only sending love and patience in return, helping the frightened skeleton slowly calm down, magic becoming more and more loose as he was bathed in the attention and love of his partner.

"MMMMHH.. SANS..." Papyrus cooed, looking lovingly into the skeletons' eyes above him, smiling brightly as he felt something move lower to his pelvic inlet, barely fitting, semi-stretching the bones to pass through.

"yer doin' great bro, keep doing what'cha doin' right now" The comforting deep words poured from his mouth, filling the shivering skeleton's soul with a warm fuzzy glow.

"NYEH....!" Papyrus whimpered, the pressure kept dropping lower, until he felt himself stretch, voice rising in volume again.

Sans' free hand rubbed the ecto-chamber, trying to soothe the pain that he could feel through the soul-bond. Something began to show through the orange folds, it was dark in color, contrasting well with bright glow of orange surrounding the object.

"somethin's comin' out paps, it might be it, stay strong" He readied his free hand below the magic, wanting to catch it when it escaped from the orange magic.

Papyrus' grip tightened, face filled with determination to see this through to the end. He looked into the bright glow of eye-lights, soul beginning to glow brighter at the connection, strengthening the already overflowing magic. He could feel himself stretch, stretch, and stretch, until... it was gone!

With a wet 'pop' sound, the egg landed in the lap of the one awaiting for it's arrival. Startled by the sudden exit, Sans could only stare at the dark glow of the object in his lap, eye-lights quivering with intensely strong emotions.

"is' is' a..." Sans could only stutter out, hand instinctively rubbing the surface of the object. It felt leathery and the surface gave-way to the pressure, creating a small but almost unnoticeable dent.

"WHAT'S THE MATTER SANS? DID YOU BREAK IT?!" Papyrus gawked, sitting up suddenly, but started to wince from over-exhaustion and pain.

Snapping back to reality, Sans' eye-lights darted to the sitting from in-front of him.

"no, no! i wouldn't break it paps, is just that... i wasn't expectin' this.." The sentence almost sounded whispered, focus returning to the object in his lap.

A larger hand over-lapped his own, snapping his attention to the other skeleton, blushing in surprise at the face surprisingly close, a love-filled gaze was all he could see.

"WELL, I LOVE IT" Papyrus whispered, clacking their teeth together, scooting closer to the shorter skeleton, wrapping his legs around the sitting from in-front of him.

"heh.. thas' all the convincin' i need bro, now.. can we go back to sleep? that experience really drained the magic out of these bones.." Wrapping his arms around the form in-front of his, forms almost touching if not for the dark glow of the object between them.

"YES, GOOD IDEA! THE GREAT PAPYRUS NEEDS HIS BEAUTY REST AFTER SUCH AN ORDEAL!" Leaning back, laying down once-more, bringing the short skeleton and object down with him, he smiled feeling the magics coercing between one another.

"WAIT- WHAT IF WE SMOOSH IT?" Papyrus panicked, eye-sockets growing wide.

"nah, it'll be fine, we're skeletons bro, we don't weigh all that much.." Sans chuckled, still laying his skull on his brother's chest, enjoying the steady and strong beat of his soul behind the shirt and rib-cage.

As the room was bathed in nothing but darkness and dead silence, the two monsters began to drift away, the world slowly melted away to whatever their minds could dream of.

Only to be suddenly awoken by the sound of the bedroom door being smashed.

The two monsters jolted awake, the left eye of the older skeleton glowing a vibrant blue, but quickly dissipated from the familiar figure in the doorway.

"UNDYNE?!" They both shouted in unison, eye's wide at the wide-grin of the fish monster.

"That's right punks!! You fools are starting to worry me, so I decided to investigate!" Undyne walked over, a grin on her face, some of her pointed teeth poking through her lips.

"But! I didn't just come here on my own! I brought my adorable and awesome lizard girlfriend!!" The fish lady seemed to almost cheer as Alphys poked her head through the door.

"Oh! Uh.... hey Sans!" Alphys chirped in, trying to sound happy despite the dark circles under her eyes,

The skeletons could only stare, the situation settling into their minds, that's until Undynes' smile began to lose it's power, turning into a slight frown the longer she looked at them.

"Why are you two sleeping in the same bed anyways? Isn't this Papyrus' room?" 

Blushes of their respective colors filled their cheekbones, faintly glowing the area around them.

"UHH.. SANS HAD A NIGHTMARE?!" Papyrus tried to reason, smiling nervously.

Undyne eyed him suspiciously, arms crossing over her chest. Alphys stepped to her side, looking at the two skeletons worriedly.

"What's the matter? Are you two sick?" Alphys questioned, reaching out a scaly clawed hand to them both.

Sans slid off of Papyrus and swung his legs over the side, looking at Alphys directly into her eyes.

"what'cha reachin' for alph?" Sans almost whispered, expression and voice calm, but aura around him felt threatening.

"O-Oh, I'm sorry! I didn't mean to uhh.." She jerked her hand back, guiltily looking away, a blush apparent on her scales.

"HOW ABOUT WE ALL HAVE A SLUMBER PARTY?" Papyrus interjects, sitting up so he could look at his friends.

Sans looked back at him in almost disbelief, opening his mouth to say something but was cut off.

"That's great! We haven't done something like this in a long time! But we uhh.." Undyne looked at her small girlfriend, smile almost sheepish.

"we'll do it downstairs, we'll meet you two down there, i just wanna discuss something with pap" Sans' smile was still lax, the threatening aura not as strong but still lingering.

"Alright! Let's go Alphys, we can start a movie down there while we wait for those dorks" Undyne wrapped her arm around the scientists' shoulders, guiding them downstairs.

Sans turned around, sitting on the bed in a crossed legs position, facing his brother.

"paps.. why'dya do that? i don't want them to find out about this... they'll find it disgusting and i don't.. i don't want you to get hurt bro.." Sans' expression softened, a soft smile on his face.

Papyrus could only smile back, cupping Sans right cheek.

"BROTHER, THEY'RE OUR FRIENDS! WHY WOULDN'T THEY BE OKAY WITH THIS? I'M SURE THEY'LL UNDERSTAND IF THEY'RE TRUE FRIENDS!" Papyrus cheered.

"yeah but.. what if they don't accept it?" Sans responded.

"...YOU WORRY TO MUCH, TRUST ME BROTHER! WE'LL BE OKAY, I PROMISE!" Papyrus cheered, pulling Sans towards him into a hug.

Clutching at the larger form, his worries almost seemed to melt away the longer he was in the soothing aura of the others' soul. But... he had monsters waiting downstairs that he didn't just want to forget about. Reluctantly, he pulled back.

"alright paps.. i trust ya.. and if anything does happen, we'll always have each-other anyways.." Sans blushed lightly, a warm fuzzy feeling coming over him from saying that.

Papyrus almost looked overjoyed, he turned around and gently grasped the egg, sitting it into his lap. The older skeleton looked at the egg, the feeling of over-protectiveness coming over him.

"OKAY! LET'S GO SANS! I AM READY FOR THIS BUT.. I'M STILL NERVOUS" Papyrus sighed, scooting off of the bed and standing tall, cradling the egg in his left arm. He reached out for the skeletal sibling with his free hand.

Sans reached for it, grabbing it as he hopped off the bed. He could feel the taller sibling shaking slightly, he clutched the hand reassuringly, helping the shaking somewhat.

Stepping over the broken pieces of wood, they make their way down the stairs, alerting the two female monsters sitting on the floor.

"There you dorks are! I was about to come get you-" Undyne cut off, seeing their hands linked and the object in Papyrus' arm.

The lizard monster shuffled to Papyrus' side, eye's seemingly bursting out of her skull at the object in his arm. But quickly her view was intercepted by Sans.

"W-Wait was that an egg?! Oh my god! Where did you guys get it?!" Alphys began to squeal, babbling about how amazing monster eggs were.

"WE.. WE GOT IT FROM.." Papyrus stuttered, cheekbones flashing an orange, head lowering in embarrassment.

"it's an interesting situation, ya see.. paps here is an omega monster.. and for him it's.. just natural to form.... uhh.. female parts instead of male ones when he's.. aroused" Sans' blush becoming brighter as the statement grew longer.

"Is that why you couldn't make it to any of our training sessions? Did that egg actually.. come from you?!" Undyne gawked.

Papyrus' head flung up, looking Undyne in the eye.

"YES.. YES! THIS EGG IS MINE.. IT'S MINE AND.. SANS'.." Papyrus continued to hold his eye-contact strong.

Alphys and Undyne just stood and began to stare, the information settling in. Instead of the expected disgusted look, they just smiled at them.

"That's great! You're the only skeletons, right? So it should only help" Alphys smiled, raising her pointed claw.

"Yeah! Of course.. it's kind of gross, but.. aw, who cares?! As long as you two are happy, right?" Undyne chortled, slapping Papyrus on the back.

"WHA.. REALLY?!" Papyrus stuttered, grasp on the egg still strong.

"Of course! Now, come on.. let's go watch that movie!" Undyne smiled, leaping over the couch and onto the floor.

Alphys followed Undyne, leaving Sans and Papyrus to stare at each-other in complete disbelief. Their disbelief slowly turning into overwhelming happiness. Walking to the couch hand-in-hand they sat behind their friends, becoming fully engrossed into the opening of the movie.


	2. An Actual Bab

**Summary for the Chapter:**

> wow an actual fucking baby gg

The job wasn't over yet, of course.. it only got harder when the egg finally hatched.

"SANS! SANSSSS!! IT'S MOVING!" Papyrus shouted worriedly, grabbing his brother's wrist and dragging him to the object he was talking about.

When reaching their destination, sure enough Papyrus was right, the egg was shaking. Some areas of it would rise up, than go back down only for another spot to rise up again.

"'s alright bro, 's just hatchin'.." Sans said nonchalantly, secretly becoming very excited.

Gasping in awe, Papyrus crouched down next to his brother, clutching him into an embrace, almost bursting into tears.

"I'M.. I'M GONNA BE A MOM!" Papyrus cried cheerfully.

"yeah paps, yer gonna be a great mom" Sans snickered, hugging his brother back, both still keeping their eye on the shaking egg.

The egg would continue to shake, the shaking only growing in power and frequency. Until the exterior of the shell began to tear, revealing the moving bone beneath.

Both of their eyes grew wider in anticipation to when the small monster would fully break free.

Power of the struggling only increased the longer it continued on, some areas wearing thin and becoming almost iridescent.

"SANS!! IT'S ALMOST OUT!!" Papyrus shook the skeleton in his grip, smile full and overjoyed.

"woah there bro, yer gonna make me sick if ya keep shakin' me like this" Sans' eye-lights began to turn into spirals.

The shaking immediately stopped, eye-lights returning to normal when the room stopped spinning for the monster. But as his vision re-focused... the egg had hatched and sitting in the remains of the shell was a small white skeleton waiting for them.

"NYEH HEH HEH!" Papyrus laughed overjoyed, hugging the newborn skeleton. Even through his overjoyed emotions he kept caution to not hurt or startle the new being.

"is' soul is kinda dark... not what i was expectin'" Sans' instincts began to scream at him that the soul looked familiar and screamed danger. But the parental instincts conflicted with the thoughts, only thinking about protecting his soulmate and new baby.

Raising the baby in the air, he smiled at the baby cheerfully.

"SAY 'PAPYRUS IS GREAT!'"

The baby just stared at him, lop-sided eye-sockets showing a blank expression.

"uhh.. it just got out bro, i dont think it can speak yet" Sans chuckled, rubbing the back of his skull.

"NONSENSE! THIS SMALL SKELETON CAME FROM SOMEONE AS GREAT AS ME!" Papyrus posed, baby still in hand.

Sticking it's arms out, the small skeleton began to flap them, making buzzing noises, small pinpricks of light appearing in their eye-sockets.

"SEE SANS?! IT'S ALREADY FLYING!!" Papyrus laughed, running around with the baby still pretending it's flying.

Sans could only laugh at the scene, marveling at how cool and goofy his brother could be.

"bro, set the little guy down for a minute... i'd like to see it.. more up-close"

"OH? WELL... SURE SANS!" Papyrus skidded to a stop, settling the baby into the green couch.

Settling on the couch, Sans coaxed the baby into his lap with sturdy hands. His eye-lights roamed the small frame, resting at the deep dark violet soul behind small ribs. Breathing from Sans stopped, his soul skipping a beat. It was so.. dark? The baby stared at him back, small hand coming to inspect the perma-grin on his face.

"AWE, SEE SANS? I THINK IT LIKES YOU ALREADY!" Papyrus clapped in celebration, heading into the kitchen. "I THINK IT'S TIME FOR SOME CELEBRATORY SPAGHETTI!" 

Eye-lights flickered to Papyrus leaving, than resting on the baby again.

The hand continued to run across his perma-grin, tips of fingers lightly scratching against the teeth.

"alright little guy, that's enough" Sans lightly clutched the small wrist, bringing it away from his face. "les' get'cha some clothes, 'm sure i still got some from when paps was a baby-bones" Sans grin widened, fond of the memories.

 

 

 


	3. WIP

Getting himself off the couch, Sans set off to his room with the baby coddled in his right arm. Footsteps could be heard climbing the stairs, and than creaking of a door.

Setting the baby on the mattress, the short skeleton began to investigate, trying to remember where he kept the clothes.

Rummaging through some piles of socks turned up nothing. That didn't stop him from trying, as his search progressed. The baby stared at him, eye-sockets almost threatening to drill holes on the back of his head.

"alright little guy... i couldn't find any, although... maybe you'd like some of my clothes? might be a little roomy though" Sans said, pulling out a plain light blue sweater.

"don't know where this came from, but alright" Sans said as he walked towards the infant, putting the sweater on the small body.

Sans could only chuckle "looks a little like a dress on ya, huh?" 

The baby's eye-sockets looked down at the soft stitching of the sweater, running it's small hand over the material. It's head perked up, eye-lights returning, along with a content noise.

Scooping the baby up in his arms, he carried it back downstairs, returning to the spot that they were at originally.

He began to actually look at the infant, noticing small details that he didn't quite notice before. It's skull had been shaped like his, but the smile wasn't permanent, and the eye-sockets... one was smaller than the other. They weren't even circular either, they represented the slits that his brother had. 

"i gotta come up with a name for ya, as much as i like callin' ya 'little guy' you might want something more... your own, right?" Sans smiled, lightly patting the baby on the back.

"uhh... how about Jack Marrow?" Sans chuckled at his own stupid pun.

"SANS! WE ARE NOT NAMING THE BABY AFTER A STUPID PUN!" His brother shouted, handing him a bowl of spaghetti.

"gutless?"

"NO!"

"alright bro... i'll take it seriously this time, 'm just gonna throw a name out... but what about jawny?" Sans laughed

"OH MY GOD!!" Papyrus exclaimed "I'LL JUST NAME IT MYSELF THAN!! UHH... LUCIDA?" Papyrus could only shrug at the suggestion.

"huh, y'now what? i could get used to that" Sans said, rubbing his chin.

"R-REALLY?- I MEAN, YES! ONLY THE GREAT PAPYRUS COULD COME UP WITH SOMETHING SO CLEVER!" Striking that signature pose after all was said and done.

After chowing down on the celebratory spaghetti, they decided that both of them should stay with the small skeleton and get to know it more.

"bro, i don't think this is gonna work out" 

"NONSENSE, BROTHER! NOW.." Papyrus leaned down, meeting the small baby's eye-level. "CAN YOU SAY 'I AM GREAT'?"

Sans could only chuckle at the blank stare the infant gave him.

"COME ON! I BELIEVE IN YOU!"

The blank stare continued.

 "HMM... MAYBE IT'S TOO SHY TO SPEAK" Papyrus spoke, scooping the baby into his arms.

"BUT DO NOT FRET! FOR I, THE GREAT PAPYRUS WILL HELP YOU IN THIS HORRIBLE DILEMMA OF STAGE FRIGHT!!" Swinging the baby over his head, smiling gleefully.

"careful there bro, ya might make it worse"

"R-REALLY..? WELL.." Papyrus slowly lowered the baby from up in the air, cradling it in his arms.

Sans walked up to his side, sitting down.

"c'mon bro, we could do somethin' else" Sans said, clacking their teeth together.

Quickly covering the babies' eyes with his gloved hand, his flustered face swung to face his brother. "SANS! THAT IS VERY INAPPROPRIATE FOR OUR CHILD TO SEE!"

"what, this?" He clacked their teeth together again.

"GAHHH! I HAVE A POST TO RUN!" Transferring the baby into Sans' lap before bolting out the door.

"heh, cool..." His eye-lights wandered down to the infant in his lap.

He could only stare at the hollow sockets, seemingly transfixed on the blank expression. It's eyes reminded him so much of Papyrus, his soul aching as the soul's ties grew weaker as the distance grew farther.

"Guhh.."

Sans' eye-lights slightly grew larger. "d-did you just speak?"

Again, that blank stare.

Sighing, Sans hoisted himself and the baby onto the couch, reaching for the remote.

"hows 'bout we watch some mettaton before paps gets back, huh?"

Clicking the power button, the T.V. lightened up to some movie about how angels come from plants.

"interesting..?"

 

 

**Author's Note:**

> ayy, i finally did it.. lets just see if i'll be able to type some more trash later.. who knows lmao


End file.
